A conventional parallel power supply device has a plurality of power supply devices connected in parallel and operates a common load. Each power supply device generates a current detection signal by detecting output current of the power supply device, compares the current detection signal of the power supply device with a current detection signal generated by another power supply device to obtain a first comparison result, compares the current detection signal of the power supply device with the first comparison result to obtain a second comparison result, and adjusts output voltage of the power supply device on the basis of the second comparison result (see, for example, Patent Document 1).
A conventional DC/DC converter used in each of the power supply devices connected in parallel in the parallel power supply device is, for example, configured as follows. In this DC/DC converter, a first switching circuit is connected between a first winding of a transformer and a DC power supply, and a second switching circuit is connected between a second winding and a battery. In the case of charging the battery, a control circuit turns off elements of a second bridge circuit in the second switching circuit, and controls, relative to a drive phase for a first reference element of a first bridge circuit in the first switching circuit, a phase shift amount for a first diagonal element thereof and a phase shift amount for a second diagonal element in a second bridge circuit. In the case of discharging the battery, the control circuit turns off elements of the first bridge circuit, and controls, relative to a drive phase for a second reference element of the second bridge circuit, a phase shift amount for the second diagonal element and a phase shift amount for the first diagonal element (see, for example, Patent Document 2).